Seat belts are standard equipment for almost every kind of vehicle in which occupants are transported in today's transportation systems. Not only are original equipment manufacturers (OEMs) required to meet strict standards for seat belt engineering and installation, but in many scenarios, vehicle occupants are required to wear seat belts as a matter of law. Even with manufacturing regulations and use laws in place, however, overall vehicle safety is entirely dependent upon vehicle occupants using seat belts properly. Visual inspection by outside authorities is not completely reliable given that a vehicle interior is only partially visible from outside of a vehicle. Individuals attempting to circumvent seat belt use laws also position seat belts inside a vehicle in a way that gives an appearance of seat belt use but allows the vehicle occupant more latitude in range of movement (i.e., fastening the seat belt behind the user's back or pulling the seat belt only partially across the user's body and manipulating the seat belt spool to maintain the seat belt in an extended position without requiring a fixed latching).
Seat belt misuse and/or unreliable seat belt monitoring may implicate issues other than simple bodily protection by restraining an occupant during an accident. Detection and tracking of occupant seat belt use has been primarily accomplished using on/off switches as sensors that transmit corresponding buckled/unbuckled data signals to a central processor as part of a vehicle control system data gathering operation. Sensor state from the seat belt switches can be used to determine restraint settings and used, for example, to determine air bag suppression or deployment decisions. Motorized seat belts may also use belt payout sensors and/or belt tension sensors, where these sensors can be used to detect and/or track proper belt placement as well as dynamic changes in the seat belt payout when the occupant is moving. Such sensors can be used to control restraint settings statically and/or dynamically.
Prior methods of seat belt monitoring can be effective but can also be spoofed. As noted above, individuals continue to engage in improper seat belt buckling behind or under the occupant, attaching buckle surrogates without using the seat belt, and maneuvering themselves out of the seat belt, particularly the shoulder strap, by hand. Furthermore, many rear seating locations do not currently use seatbelt switches, belt payout sensors, or belt tension sensors. It may be difficult to install the necessary electronics in adjustable and movable seating locations to support buckle switches, payout or tension sensors as aftermarket control hardware.
A need continues to exist in the vehicle market for control systems that monitor vehicle occupants for proper seat belt use and provide seat belt use and position data to the control system to enact additional safety precautions as discussed herein.